Headstack locator assembly for testing magnetic heads

ABSTRACT

A headstack locator assembly for locating and fixing a headstack on a spinstand and which mitigates the aforementioned prior art limitations. The headstack locator assembly includes a headstack locator received on a fixed locator. The headstack locator connects to a headstack, while the fixed locator is permanently secured to a spinstand. A vacuum is used to clamp the headstack locator to the fixed locator for testing of the headstack. Upon test completion, the headstack locator is released from the fixed locator by applying positive air pressure to the assembly.

FIELD OF THE DISCLOSURE

The present disclosure relates to testing of components of hard drivesfor computers, and, specifically, it deals with a system for locatingand fixing a headstack, which is a part of a hard disk assembly, in aheadstack tester.

BACKGROUND OF THE DISCLOSURE

Modern computers have hard drives that are made in the form of aheadstack and a stack of hard disks. A headstack is an assembly thatincludes one or more read and write heads, which are stacked in such amanner as to work in conjunction with the pack of hard disks, which areused for data storage. These devices are well known and are used in manydata storage applications. The headstacks are manufactured by manycompanies such as SAE Magnetics, Western Digital (Read-Rite), HitachiGlobal Storage Technologies (IBM), Seagate, and others. The headstack isgenerally mounted on a shaft by means of bearings, which allows theheadstack to rotate freely on the shaft. During data storage operations(reading and writing), the magnetic heads are turned on the shaft toposition them with respect to the hard disks.

A magnetic head and disk tester is an instrument that is used fortesting the characteristics of magnetic heads and disks, such as asignal-to-noise ratio, track profile, etc. The tester simulates thosemotions of the head with respect to the disk and the same rotationalspeeds of the disks that occur in an actual hard disk drive duringoperation. Each tester consists of two components, i.e., a mechanicalcomponent, commonly referred to as a spinstand, that performs movementsof the head with respect to the disk, and an electronic component thatis responsible for measurement, calculation, and analysis of themeasured signal. The spinstand is also a mechanical component of aservo-writer, an instrument that is used for writing servo informationon a magnetic disk, as well as a component of a flying height tester; aninstrument used for measuring the flying height of a head over the disk.

An example of a prior art spinstand for a head and disk tester isillustrated in FIGS. 1 and 2. The spinstand 100 includes a stationarybase plate 110 that supports walls 112 a, 112 b, 112 c. The walls 112 a,112 b, 112 c in turn support a spindle 113 for carrying a disk pack DPdisposed in a cylindrical disk pack region including one or moremagnetic disks 114, having diameter D, and being coaxial about a diskpack axis DPA. The spindle 113 and the disks 114 are rotated by aspindle motor 115 about a spin axis SA.

The base plate 110 further supports first and second slide motors (notshown). The first slide motor moves a slide 116 along rails 117 a, 117 bin the Y direction (see FIG. 2). Two additional rails, 118 a, 118 b, aremounted on top of slide 116. The second slide motor controls movement ofa second slide 119 along rails 118 a, 118 b in the X direction. Thefirst and second motors cooperate to position a headstack 120 mounted ona headstack locator 121 of the slide 119 to a specified location withrespect to the center of spindle 113. The headstack 120 carries andpositions magnetic head(s) 122 relative to disk(s) 114.

Other examples of prior art spinstands for a head and disk testerinclude the Guzik V2002 XY-positioning spinstand and the Guzik S-1701Series Micro Positioning Spinstand, all of which are available from theassignee of the present disclosure, Guzik Technical Enterprises, 2443Wyandotte Street, Mountain View, Calif. 94043, USA (www.guzik.com).

As the density of magnetic recording increases, additional informationtracks are compressed into a given disk area. The decrease in track sizeheightens the demand for improved accuracy in head positioning.Likewise, the rotational speeds of the magnetic disks increase in orderto achieve shorter access times. In addition, more disks are added tothe disk stack to provide additional storage.

As the disk(s) rotate, vibrations in both the disks and the magneticheads may be induced. These vibrations increase track misregistration.In some cases, track misregistration between the disks and the magneticheads reaches unacceptable levels at which spinstand operation becomesunreliable.

What is still desired is a new and improved apparatus and method forlocating and fixing a headstack on a spinstand. Among other aspects andadvantages, the new and improved apparatus and method will quickly andaccurately locate and secure a headstack to a spinstand for testing,while retaining the reliability and stability of all previous methods.

SUMMARY OF THE DISCLOSURE

The present disclosure is directed to a new and improved headstacklocator assembly for locating and fixing a headstack on a spinstand andwhich mitigates the aforementioned prior art limitations. According toone exemplary embodiment of the present disclosure, the new and improvedheadstack locator assembly includes a headstack locator received on afixed locator. The headstack locator connects to a headstack, while thefixed locator is permanently secured to a spinstand. A vacuum is used toclamp the headstack locator to the fixed locator for testing of theheadstack. Upon test completion, the headstack locator is released fromthe fixed locator by applying positive air pressure to the assembly.

In one form, the fixed locator includes a fixed locator bushing and apin receiving aperture. The fixed locator bushing is disposed about andextends transverse to the fixed locator axis. The fixed locator bushinghas an upper surface extending transverse to the fixed locator axis.

The pin receiving aperture extends from the fixed locator bushing alongthe fixed locator axis. The pin receiving aperture has a contour with acircular cross-section having a radius which monotonically decreasesfrom the upper surface of the fixed locator bushing.

The pin receiving aperture extends from a region adjacent to the uppersurface of the fixed locator bushing to a port. The port is adapted toreceive an applied vacuum and an applied positive pressure.

The headstack locator extends along a headstack locator axis andincludes a headstack locator and a locating pin. The headstack locatorbushing has an upper surface and a lower surface and is disposed aboutand extends transverse to the headstack locator axis. The headstacklocating bushing has a lower surface extending transverse to theheadstack locating axis. The headstack locating bushing has on its uppersurface, a coupling assembly for receiving a headstack having aheadstack axis, whereby the headstack axis is coaxial with the headstacklocator axis.

The locating pin extends from the lower surface of the headstack locatorbushing along the headstack locator axis. The locating pin has an outercontour with a circular cross-section having a radius which decreasesmonotonically from the lower surface. The contour of the locating pin issubstantially complimentary to the contour of the pin receivingaperture.

The headstack mounting assembly further includes a sleeve extendingalong a sleeve axis. The sleeve extends from a peripheral surface of thefixed locator bushing. In alternative embodiments, the sleeve extendsfrom a peripheral surface the headstack locator bushing. In thoseembodiments, the sleeve axis is coaxial with a corresponding one of thefixed locator axis and the headstack locator axis and the other of thefixed locator bushing and the headstack locator bushing is positionablewithin the sleeve with the fixed locator axis, the headstack locatoraxis and the sleeve axis being coaxial when the pin is disposed withinthe pin receiving aperture.

In a preferred form of the invention, the headstack mounting assemblyfurther includes a seal disposed on one of a peripheral surface of thefixed locator bushing and a peripheral surface of the headstack locatorbushing. The seal pneumatically isolates a region between the uppersurface of the fixed locator bushing and the lower surface of theheadstack locator bushing and within the sleeve. The seal pneumaticallycouples the region to regions outside the headstack mounting assemblywhen a positive pressure is applied to the port.

In use, when the pin is disposed within the pin receiving aperture and avacuum is applied to the port, the static pressure in the region,responsive to the applied vacuum and ambient pressure outside theassembly, biases the head locater bushing toward the fixed locatorbushing, thereby coupling the headstack locator to the fixed locator.

When the headstack locator is coupled to the fixed locator in thismanner, a positive pressure may be applied to the port, in order torelease the headstack locator from the fixed locator. Then, the staticpressure in the region, responsive to the positive pressure and ambientpressure outside the assembly, biases the headstack locator bushing awayfrom the fixed locator bushing, thereby decoupling the headstack locatorfrom the fixed locator.

In a preferred form of the invention, the seal is a u-cup wiper sealdisposed in a groove in a peripheral surface of the fixed locaterbushing. In alternative embodiments, the seal is a U-cup wiper sealdisposed in a groove in a peripheral surface of the headstock locatorbushing.

In one form of the invention, the channel extends from the port andthrough the fixed locator bushing, to the region adjacent to the uppersurface of the fixed locator bushing. In that form, the material forminga distal tip of the locating pin may be resilient relative to a materialforming the pin aperture, thereby effecting an embodiment with minimalwear on the pin and pin aperture over long usage.

In another form of the invention, the channel extends within thelocating pin from a distal tip thereof, along the headstack locatoraxis, to a lateral port in the pin at a region adjacent to the uppersurface of the fixed locator bushing.

Among other aspects and advantages, the new and improved assemblyquickly and accurately locates and secures a headstack to a spinstandfor testing.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the presentdisclosure will be apparent from the more particular description ofexemplary embodiments of the disclosure, as illustrated in theaccompanying drawings in which like reference characters refer to thesame parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the disclosure.

FIG. 1 is a schematic front view of a prior art spinstand;

FIG. 2 is a schematic top view of the spinstand in FIG. 1;

FIG. 3 is a side elevation view, partially in section, of an exemplaryembodiment of an assembly constructed in accordance with the presentdisclosure for locating and fixing a headstack on a spinstand, andincluding a headstack locator received on a fixed locator;

FIG. 4 is a side elevation view of the headstack locator of FIG. 3;

FIG. 5 is an exploded, side elevation view of the headstack locator ofFIG. 3;

FIG. 6 is a side elevation view, partially in section, of the fixedlocator of FIG. 3;

FIG. 7 is an exploded, side elevation view, partially in section, of thefixed locator of FIG. 3;

FIG. 8 is a side elevation view of a bushing of the headstack locator ofFIG. 3;

FIG. 9 is a top plan view of the bushing of the headstack locator ofFIG. 3;

FIG. 10 is a side elevation view of a bushing of the fixed locator ofFIG. 3;

FIG. 11 is a top plan view of the bushing of the fixed locator of FIG.3;

FIG. 12 is a side elevation view of the assembly of FIG. 3 showing thefixed locator secured to a slide of a spinstand and the headstacklocator prior to being received on the fixed locator;

FIG. 13 is a side elevation view, partially in section, of the assemblyof FIG. 3 showing the headstack locator received on and being secured tothe fixed locator via the application of a vacuum to the fixed locator;

FIG. 14 is a side elevation view, partially in section, of the assemblyof FIG. 3 showing the headstack locator received on the fixed locatorand being released from the fixed locator via the application ofpositive pressure to the fixed locator;

FIG. 15 is a side elevation view, partially in section, of the assemblyof FIG. 3 showing the headstack locator received on and being secured tothe fixed locator via the application of a vacuum, and wherein anexemplary embodiment of a headstack is shown secured to the headstacklocator;

FIG. 16 is an exploded sectional view of another exemplary embodiment ofan assembly constructed in accordance with the present disclosure forlocating and fixing a headstack on a spinstand, and including aheadstack locator received on a fixed locator;

FIG. 17 is an assembled sectional view of the headstack locator of FIG.16;

FIG. 18 is an exploded side elevation view, partially in section, ofanother exemplary embodiment of an assembly constructed in accordancewith the present disclosure for locating and fixing a headstack on aspinstand, and including a headstack locator received on a fixedlocator; and

FIG. 19 is an assembled side elevation view, partially in section, ofthe headstack locator of FIG. 18.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring first to FIGS. 3 and 12-15, there is shown an exemplaryembodiment of an assembly 10 constructed in accordance with the presentdisclosure for locating and fixing a headstack on a spinstand. Theassembly 10 includes a headstack locator 12 received on a fixed locator14. The headstack locator 12 connects to a headstack 120 (as shown inFIG. 15 for example), while the fixed locator 14 is permanently securedto a slide 119 of a spinstand. A vacuum is then used to clamp theheadstack locator 12 to the fixed locator 14 for testing of theheadstack 120. Upon test completion, the headstack locator 12 isreleased from the fixed locator 14 by applying positive air pressure tothe assembly 10.

Among other aspects and advantages, the new and improved assembly 10quickly and accurately locates and secures a headstack to a spinstandfor testing.

Referring to FIGS. 3-5, the main components of the headstack locator 12include a piston ring 16 receiving a bushing 18, which in turn receivesa locating pin 20 through a central opening. The locating pin 20includes means at one end for attaching to a headstack. In the exemplaryembodiment shown, the means comprises a threaded portion 22. Thethreaded portion 22 screws into a pivot bearing 121 of a headstack 120to secure the headstack to the headstack locator 12, as shown best inFIG. 15. The other end of the pin 20 is used to easily guide andaccurately locate, without binding, the headstack locator 12 into thefixed locator 14, as shown in FIGS. 3 and 12-15. The bushing 18 issecured to the piston ring 16 in a suitable manner, such as by beingpress fit into the ring. The piston ring 16 functions as thesealing/bearing surface between the headstack locator 12 and the fixedlocator 14, as shown in FIG. 3.

The headstack locator 12 also includes an O-ring 24 that provides a sealbetween the locating pin 20 and the bushing 18. The locating pin 20 isheld in place with two retaining clips 26, which sandwich the bushing 18onto the locating pin 20. By using the O-ring 24 and retaining clips 26for locating the pin to the headstack bushing, the locating pin isallowed to rotate. This prevents over-tightening of the locating pin 20which can cause damage to the headstack. In an alternative embodiment,the locating pin 20 can be fixed to the bushing 18, by being press-fitor glued to the bushing, without having the ability to rotate in theheadstack bushing 18. This alternative embodiment would not use theO-ring or retaining clips.

A plastic button 28 is glued into the tip of the locating pin 20 toprotect the mating surfaces of the locating pin 20 and the fixed locator14. A portion of the locating pin 20 is narrowed near the tip to easilyguide the locating pin 20 into the bore of the fixed locator 14 withoutbinding.

The bushing 18 of the headstack locator 12 is also shown in FIGS. 8 and9. The bushing 18 of the headstack locator 12 includes an annular cup 36on a top face 38 of the bushing for receiving a headstack 120, as shownin FIG. 15. As shown best in FIG. 9, the bushing 18 also has equallyspaced pads 30 on a bottom face 32 thereof. The pads 30 define a heightand parallelism of the headstack locator 12 with respect to a top face54 of a bushing 40 of the fixed locator 14. The pads 30 are receivedagainst a top annular surface 34 of the bushing 40 of the fixed locator14. By using equally spaced pads 30 instead of a solid surface, theheadstack locator 12 is less likely to rock due to mating surfacescratches or imperfections. In the exemplary embodiment shown, theheadstack locator 12 is provided with three of the equally spaced pads30. In an alternative embodiment, the annular surface is provided on thebushing 18 of the headstack locator 12 while the pads 30 are provided onthe fixed locator 14.

Referring to FIGS. 12-15, the fixed locator 14 is secured to a slide 119of a spinstand, with bolts 64 for example. As shown in FIGS. 3, 6, and7, the fixed locator 14 includes a bushing 40, a wiper seal 42, apneumatic barb fitting 44, and a washer seal 46 for the barb fitting.The bushing 40 includes a head 48 and a neck 50. The barb fitting 44 isscrewed into the neck 50 of the bushing 40. From the fitting, vacuum isdrawn and positive air pressure is applied to a centrally located bore52 of the bushing 40 of the fixed locator 14. The central bore 52extends to a top face 54 of the bushing 40 and provides two functions:delivery of negative and positive air pressure to the face 54 of thebushing, and as a receptacle for receiving the locating pin 20 of theheadstack locator 12. The head 48 and neck 50 of the bushing 40 alsodefine two ports 56, which are cross-drilled from the top face 54 to thecentral bore 52. The ports 56 allow vacuum/pressure to be applied moreevenly to the entire top face 54.

In an alternative embodiment 300 shown in FIGS. 16 and 17, the head 48and neck 50 of the bushing do not define two ports that arecross-drilled from the top face 54 to the central bore 52. Instead theassembly 300 has a locating pin 320 defining a central port 324extending upwardly from a tip of the pin (the pin 320 also includes athreaded portion 322 at a top end for attachment to a headstack). Thepin 320 also defines two ports 326 cross drilled to the center port 324.The ports 324, 326 deliver positive and negative air pressure from thebarb fitting 44 to the space located between the bushings 18, 40.

The wiper seal 42 is received in a circumferential groove 58 in a sidewall of the head 48 of the bushing 40 of the fixed locator 14. The wiperseal 42 creates a seal between the side wall of the bushing 40 and aninner surface of the piston ring 16 of the headstack locator 12. In theexemplary embodiment shown, the wiper seal comprises a U-cup wiper seal42. As shown in FIGS. 3, 6, 7, and 12-14, the U-cup wiper seal 42 has aY-shaped cross-section including a base portion 60 and two arms 62extending from the base portion. One of the arms 62 is biased againstthe circumferential groove 58 of the head 48 of the bushing 40 of thefixed locator 14, while the other arm 62 is biased against the pistonring 16 of the headstack locator 12 when the headstack locator 12 isreceived over the fixed locator 14. The arms 62 are shaped and adaptedto provide an air-tight seal between the headstack locator 12 and thefixed locator 14 when a vacuum is applied to the fixed locator 14 inorder to secure the headstack locator 12 onto the fixed locator 14. Thearms 62 are also shaped and adapted to eventually break the seal betweenthe headstack locator 12 and the fixed locator 14 when positive airpressure is applied through the fixed locator 14 to release theheadstack locator 12 from the fixed locator 14. The collapsing of arms62 of the seal 42 reduces the friction between the seal 42 and thepiston ring 16. In doing so, the number or particles generated from theseal 42 due to friction is reduced. In an alternative embodiment 400, asshown in FIGS. 18-19, the seal 42 can be located on the headstacklocator 12 and the piston ring 16 can be located on the fixed locator14.

The headstack locator 12 functions as a quick and accurate interfacebetween a headstack and a spinstand test fixture. The fixed locator 14functions as an accurate locating device for the headstack locator 12.Negative (vacuum) and positive air pressure is used to lock and release,respectively, the headstack locator 12 to the fixed locator 14. Duringnormal operation, the headstack locator 12 is assembled to a headstack.The headstack locator 12 is then inserted onto the fixed locator 14 byguiding the locating pin 20 into the central bore of the fixed locator14. The U-cup wiper seal 42 is designed, such that at ambient pressures,the locating piston sleeve 16 easily slides over the U-cup/wiper seal42. Vacuum to the fixed locator 14 is then turned on and the headstacklocator 12 is locked onto the fixed locator 14 by the vacuum.Application of the vacuum to the fixed locator 14 is illustrated in FIG.13.

When the vacuum is turned off the headstack locator 12 is difficult toremove from the fixed locator 14. To release the headstack locator 12,positive air pressure is applied through the fixed locator 14, such thatthe headstack locator 12 elevates from the fixed locator 14 and allowsan operator to easily remove the headstack locator 12. The airflow iscontrolled such that the headstack locator 12 safely releases from thefixed locator 14 without fully ejecting. Application of the positive airpressure to the fixed locator 14 is illustrated in FIG. 14.

While this disclosure has been particularly shown and described withreferences to exemplary embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of thedisclosure.

1. A headstack mounting assembly for releasably coupling a headstack toa slide of a spinstand, comprising: a fixed locator comprising a firstplanar surface, and adapted to be affixed to said slide; a headstacklocator comprising a second planar surface; and three pads, each of saidpads extending from one of said first planar surface and said secondplanar surface; wherein the headstack locator is adapted to receive aheadstack, and is adapted to be selectively coupled to said fixedlocator in response to an applied vacuum between said first planarsurface and said second planar surface, whereby said first planarsurface is opposite said second planar surface, and to be selectivelydecoupled from said fixed locator in response to an applied positivepressure between said first planar surface and said second planarsurface, and wherein, during coupling, the first and second planarsurfaces are drawn towards each other in response to the applied vacuum,and the three pads maintain separation of said surfaces.
 2. An assemblyaccording to claim 1, wherein said fixed locator extends along a fixedlocator axis, and includes: i. a fixed locator bushing disposed aboutand extending transverse to said fixed locator axis, said fixed locatorbushing having an upper surface extending transverse to said fixedlocator axis, ii. a pin receiving aperture extending from said fixedlocator bushing along said fixed locator axis, said pin receivingaperture having a contour with a circular cross-section having a radiuswhich monotonically decreases from said upper surface of said fixedlocator bushing, iii. at least one airflow channel extending from aregion adjacent to said upper surface of said fixed locator bushing to aport, said port being adapted to receive an applied vacuum and anapplied positive pressure, and wherein said headstack locator extendsalong a headstack locator axis and includes: i. a headstack locatorbushing having an upper surface and a lower surface and is disposedabout and extending transverse to said headstack locator axis, saidheadstack locating bushing having a lower surface extending transverseto said headstack locating axis, and including on said upper surface, acoupling assembly for receiving a headstack having a headstack axis,whereby said headstack axis is coaxial with said headstack locator axis,ii. a locating pin extending from said lower surface of said headstacklocator bushing along said headstack locator axis, said locating pinhaving an outer contour having a cross-section with a circularcross-section having a radius which decreases monotonically from saidlower surface, said contour of said locating pin being substantiallycomplimentary to said contour of said pin receiving aperture, andfurther including a sleeve extending along a sleeve axis, said sleeveextending from a peripheral surface of one of said fixed locator bushingand said headstack locator bushing, whereby said sleeve axis is coaxialwith a corresponding one of said fixed locator axis and said headstacklocator axis, and wherein the other of said fixed locator bushing andsaid headstack locator bushing is positionable within said sleeve withsaid fixed locator axis, said headstack locator axis and said sleeveaxis being coaxial when said pin is disposed within said pin receivingaperture.
 3. An assembly according to claim 2 further including a sealdisposed on one of a peripheral surface of said fixed locator bushingand a peripheral surface of said headstack locator bushing whereby saidseal pneumatically isolates a region between said upper surface of saidfixed locator bushing and said lower surface of said headstack locatorbushing and within said sleeve, when said pin is disposed within saidpin receiving aperture and a vacuum is applied to said port, wherebystatic pressure in said region, responsive to said applied vacuum andambient pressure outside said assembly, bias said head locater bushingtoward said fixed locator bushing, thereby coupling said headstacklocator to said fixed locator, and whereby said seal pneumaticallycouples said region to regions outside said headstack mounting assemblywhen a positive pressure is applied to said port, whereby staticpressure in said region, responsive to said positive pressure andambient pressure outside said assembly, bias said headstack locatorbushing away from said fixed locator bushing thereby decoupling saidheadstack locator from said fixed locator.
 4. An assembly according toclaim 3 wherein said seal is a u-cup wiper seal disposed in a groove ina peripheral surface of said fixed locater bushing.
 5. An assemblyaccording to claim 3 wherein said seal is a U-cup wiper seal disposed ina groove in a peripheral surface of said headstock locator bushing. 6.An assembly according to claim 1 wherein said channel extends from saidport and through said fixed locator bushing, to said region adjacent tosaid upper surface of said fixed locator bushing.
 7. An assemblyaccording to claim 6 wherein a material forming a distal tip of saidlocating pin is resilient relative to a material forming said pinaperture.
 8. An assembly according to claim 1 wherein said channelextends within said locating pin from a distal tip thereof, along saidheadstack locator axis, to a lateral port in said pin at a regionadjacent to said upper surface of said fixed locator bushing.
 9. Theheadstack mounting assembly of claim 1, wherein the headstack locatorcomprises the three pads.
 10. The headstack mounting assembly of claim1, wherein the fixed locator comprises the three pads.
 11. The headstackmounting assembly of claim 1, wherein the three pads are equally spacedacross one of: the first planar surface, the second planar surface.